As a conventional art, as disclosed in Patent Document 1, a driving force distributing device configured in a manner that a left hydraulic clutch and a right hydraulic clutch are arranged respectively on left and right sides of a hypoid gear or a bevel gear coupled to a rear end of a propeller shaft for distributing driving force (so-called “torque distribution”) transmitted from a driving source such as an engine to each of a pair of left and right wheels (left and right rear wheels) is known to be available.
The driving force distributing device disclosed in Patent Document 1 is configured to regulate pressure of hydraulic fluid discharged from an oil pump driven by an electric motor using a linear solenoid valve (pressure regulating valve), and due to this hydraulic pressure of hydraulic fluid, selectively engage two hydraulic clutches installed to each of left and right axles of the rear wheels. And, a hydraulic fluid supply device for supplying hydraulic fluid to the two hydraulic clutches includes two oil pumps respectively corresponding to the two hydraulic clutches and two linear solenoid valves for regulating pressure of hydraulic fluid discharged from the two oil pumps.
However, in this configuration, each of the two hydraulic clutches requires a pair of oil pump and rear solenoid valve, possibly leading to increase in size, weight and cost of the structure of the hydraulic pressure supply device.
Moreover, a hydraulic control device of a wet-type multiple disc clutch disclosed in Patent Document 2 is configured to send hydraulic fluid to a wet-type multiple disc clutch using an oil pump driven by an electric motor.
In the hydraulic control device disclosed in Patent Document 2, one wet-type multiple disc clutch involves one set of an oil pump, an electric motor and a motor driver. Thus, this configuration requires two sets of the oil pump, the electric motor and the motor driver are required for hydraulic control of each of the pair of right and left hydraulic clutches. Therefore, in this case also, having a large parts count, the hydraulic pressure supply device might increase in size, weight and cost of the structure.